The present invention relates generally to fitting connections for coupling the end of a length of corrugated metal tubing to another member, and more particularly to such connections which are of a pre-assembled, push-in variety.
Corrugated metal tubing, often fabricated of stainless steel, copper, or the like and jacketed with a plastic material, is commonly employed in residential or commercial building constructions as a transitional fluid conduit extending between an appliance or other machine and a rigid auxiliary line, pipe, or other connection of a fuel source which may be natural gas, propane, or the like. The flexibility of such tubing facilitates the alignment of couplings and other connections, and also accommodates limited movement of the appliance or machine with respect to the rigid connection of the fuel source.
Recently, tubing of such type, and particularly corrugated stainless steel tubing (“CSST”), has been employed as a substitute for traditional hard, i.e., inflexible, steel or iron “black” pipe in gas line applications for residential and commercial construction. Advantageously, the flexibility of the tubing facilitates its installation through walls, ceilings, and floors and, especially, the alignment of the tubing connections. Such tubing, moreover, is lightweight, easy to carry, requires no threading or heavy equipment therefor, allows the use of fewer fitting connections, and exhibits less leak potential than conventional, hard piping. Corrugated tubing of the type herein involved additionally is used in other fluid transport applications such as in air conditioning, hydraulics, and general plumbing, and also as conduit for electrical applications. Tubing manufacturers include the Parflex Division of Parker-Hannifin Corp., Ravenna, Ohio, Titeflex Corp., Springfield, Mass., OmegaFlex, Inc., Exton, Pa., and Wardflex Manufacturing, Blossburg, Pa.
Compression and other fitting connections are commonly used in gas line and other applications. As is shown, for example, in commonly-assigned U.S. Pat. Nos. 6,036,237 and 6,019,399, in U.S. Pat. Nos. 6,428,052; 6,173,995; 6,079,749; 5,799,989; 5,441,312; 5,292,156; 5,226,682; 5,080,405; 4,904,002; 4,630,850; 4,674,775; 2,549,741; and 2,323,912, and in U.K. Patent No. 1,371,609, such connections typically involve a nut and an associated collet, split ring, ferrule, flare, C-ring or rings, bushing, sleeve, or other compression or locking member which is received in or over the tube end for holding the tube end within the nut as the nut is tightened onto a nipple, adapter, body, or other connector.
As the use of corrugated tubing in gas line and other fluid transfer applications continues to increase, it will be appreciated that further improvements in the design of fitting connections therefor would be well-received. A preferred design would be economical to manufacture, but would also simplify the assembly of the coupling while providing a connection which minimizes the potential for leaks and the like.